We had some Linux VM's that were patched and noticed that some of the application started before the OneAgent. Is there any tricks anyone knows to ensure that the OneAgent is started before any applications on a server to ensure monitoring?
It's not an issue. The oneagent daemon (the part that runs as separate processes) does not affect deep monitoring.
Deep monitoring is activated on the application startup by preloading the liboneagent.so library to every process. This activation is independent from the start of the Oneagent daemon. The only case I can think of would be that the agent was removed or switched to infrastructure mode when agents were restarted.
If some applications are not instrumented, try inspecting the logs and inspect the /etc/ld.so.preload.
True, but what we seen this last weekend after some server patching with a couple of Linux VM's is that the applications actually got started before the OneAgent resulting in the applications needing to be restarted. First time I have seen this.
Well definitely it is not because the oneagent process was started prior to the application processes. There must be another reason for this.
My thought is that it is somewhat like when you first install the OneAgent. It often requires specific things to be restarted so that Dynatrace can gain full visibility. It's strange for sure... First time I have seen it.
Understood... Anything interesting in the agent logs on the host?
Did you wait some time after host startup? Sometimes there is message about restart needed but it disappears after few minutes and monitoring is working fine. sebastian